Sheet feed mechanism for paper

ABSTRACT

Apparatus is described for individually feeding flexible sheets from a stack thereof. Roller means drive the top sheet of the stack off the remainder of the stack while a pair of hinged and weighted pressure members, in frictional engagement with the top sheet, produce displacement of the trailing corners of the sheet toward each other and thereby cause the top sheet to buckle and separate from the sheet below.

United States Patent [72] Inventor Louis A. Smitzer 3.408.064 10/1968Johnson et al. 271/61 San Diego, Calif. 2,266,068 12/1941 Peterson et a1271/61 {21] Appl. No. 749.436 3,369,804 2/1968 Schulze et a1 271/21 [22]Filed Aug. 1,1968 3,285,601 11/1966 Zeuthen 271/17 [45] Patented June22,1971 3,260,521 7/1966 Moxness... 271/39 [73] Assignee StrombergDatagraphics lnc. 1.l96,36l 8/1916 Howell 271/22 San Diego, Calif.2,827,288 3/1958 Geisler 271/24 FOREIGN PATENTS 1,127,374 41962 G 2711954 SHEET FEED MECHANISM FOR PAPER I many 2 Claims, 4 Drawing Figs.Primary Examiner-Evon C. Blunk Assistant ExaminerH. B. Lane [52] US. Cl22771103691, Anomey Anderson Luedeka Fitch Even and Tabin [51] lnt.ClB65h U013 Field of Search 27H, ABSTRACT: Apparatus is described forindividually feeding 36, 61, 62 flexible sheets from a stack thereof.Roller means drive the top [56] R f (Tied sheet of the stack 05 theremainder of the stack while a pair of e emnces I hinged and weightedpressure members, in frictional engage- UMTED STATES PATENTS ment withthe top sheet, produce displacement of the trailing 2,285,224 6/1942Nigra et al. 271/61 UX corners of the sheet toward each other andthereby cause the 3,104,873 9/1963 Benson et a1. 271/61 top sheet tobuckle and separate from the sheet below.

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LOUIS SMITZER SHEET FEED MECHANISM FOR PAPER This invention relates tofeeding apparatus and, more particularly, to apparatus for individuallyfeeding flexible sheets from a stack thereof, such as may beincorporated in printing machines and copying machines.

in some types of machines, it is desirable to provide apparatus forindividually feeding flexible sheets from a stack thereof. Thus, in manytypes of printing machines and copying machines, a supply of paper isprovided in the form of a stack of sheets of uniform length and width.Since only one sheet is used at a time, apparatus is provided forautomatically separating one sheet from the stack and feeding it intothe remainder of the machine for processing. For reliable operation,such feeding apparatus should be capable of individually feeding sheetsfrom a stack which may vary in height from only two sheets to aconvenient maximum capacity, which may be a hundred or more. Generally,the sheets should be fed in singly and with a proper and consistentlyuniform orienta tion. It is frequently desireable that the apparatus becapable of feeding sheets of a variety of thicknesses or surfacequalities.

Heretofore, apparatus capable of operating as described above hasfrequently been of complex construction. Not only does high complexitytend to diminish reliability, but it also tends to maintain the cost ofthe apparatus at a relatively high level. This may be a substantialfactor in maintaining the total cost of the machine, of which the feederapparatus is a part, undesirably high.

It is an object of this invention to provide improved apparatus forindividually feeding flexible sheets from a stack thereof.

Another object of the invention is to provide feeding apparatus which isof simple construction and is reliable in operation.

A further object of the invention is to provide feeding apparatuscapable of operation with a variety of stack heights and with sheets ofvarying thicknesses and surface qualities.

Other objects of the invention will become apparent to those skilled inthe art from the following description, taken in connection with theaccompanying drawings wherein:

FIG. 1 is a full section side view of a preferred form of apparatusconstructed in accordance with the invention, showing an alternateposition of a portion of the apparatus in phantom;

FIG. 2 is a front view of the apparatus, with part broken away, and alsoshowing an alternate position of a portion of the apparatus;

FIG. 3 is a top view ofa part of the apparatus and;

FIG. 4 is a view of the back edge of the stack of paper which theapparatus feeds taken along the line 4-4 of FIG. 3.

Very generally, the apparatus of the invention comprises means forsupporting the stack 11 of sheets and roller means 12 disposed to be infrictional engagement with the top sheet 13 of the stack. A pair ofpressure members, l4, 15, are disposed to be in frictional engagementwith the top sheet of the stack at regions toward the trailing edge ofthe top sheet at the side edges thereof. The region of engagementbetween the roller means and the top sheet is located toward the leadedge of the top sheet inwardly from the side edges thereof a distancesufficient to cause the pressure members to produce inward displacementof the sides of the sheet toward each other near the trailing edge whenthe roller means are turned to feed the top sheet. This causes the topsheet to buckle further and separate from the sheet beneath it.

Referring now more particularly to the drawings, the apparatusillustrated therein is useful in connection with an automatic copyingmachine. In its illustrated form, the apparatus of the inventionprovides a supply of copy paper in the form of a stack 11 of sheets ofuniform length and width, feeding only one sheet at a time by separatingone sheet from the stack and feeding it into the copying portion of themachine (not shown). The mechanism operates reliably with a stack of anyheight from two sheets to the maximum capacity depending upon the sheetthickness. Sheets are not double fed or fed in improper orientation, andthe apparatus is capable of operating with papers of differentthicknesses and surface quality.

The stack ill of paper is supported on support means consisting of atray 10, disposed at about a 30 angle to the horizontal. The tray 10includes a floor 16, a back 17, and two sides l9 and 21. The side 19 isprovided with two out out sections 23 and 25. Similarly, the side 21 isprovided with two out out sections 27 and 29. The tray may be made wideenough and long enough to receive 8 1% by 13 inch sheets. An adapter,not shown, may be placed in the tray to reduce its interior dimensionsif a different sheet size is to be used.

The top sheet 13 of the paper stack 11 is disposed in engagement, nearits forward or leading edge 33, with the roller means l2. The rollermeans comprise a pair of cylinders 37 and 39 mounted on axle 41 andspaced from each other and from the outer edges of the tray such thatthe outer most edges of the rollers are at a position about one-third ofthe distance in from the sides of the tray. The cylinders are each about1 52 inches in diameter. The axle 41 is rotatably driven by a motor, notshown, and is intermittently coupled to the motor by a clutch, also notshown. The outer surfaces of the cylinders 37 and 39 are coated with aresilient material, such as resilient polyurethane, which is capable ofgripping the top sheet of the paper with a frictional force for a widevariety of surface qualities.

As will be explained, the axle 41 is rotated to cause the cylinders 37and 39 to turn in the direction of the arrows indicated and feed the topsheet 13 toward a pair of takeup rollers 43 and 45. The takeup rollers,which may be constantly rotating in the direction of the arrowsindicated, grip the leading edge of the top sheet as it is fedtherebetween and pass it on to the remainder of the copy machine forprocessing in a suitable manner.

The tray 10 is supported by a base 47 having a horizontal plate joininga pair of side plates 49 and 51. The tray is secured to the base at thesideplates plates 49 and 51 thereof by means of a pair of pivotassemblies 53. The side plates 49 and 51 of the base d7 are supported bysuitable drawer slide assemblies, not shown, to be horizontally movablein the frame or cabinet of the copy machine. This facilitates loading,as will be described in detail below.

A retainer plate 57 is also supported by the base 47, being pivotallysecured to the side plates 49 and 51 thereof by the pivot assemblies 53.The end of the retainer plate 57 opposite the pivot assemblies 53 issupported between a pair of latch plates 59 by a pair of latch pins 63.The latch plates are bolted to the sideplates 49 and 51 of the base 47and extend upwardly therefrom. Each latch plate has an aperture formedtherein for receiving the ends of the latch pins. The latch pins arecarried in a latch tube 62 and are biased against the latch plates by asuitable spring or springs, not shown. Knobs 64, extending through aslot in the tube 62, enable the latch pins to be manually pulled towardeach other and away from the latch plates. When released from the latchplates 59, the latch pins support the retainer plate by retaining on apair of brackets 61 which are secured to the side plates 49 and 51 sothat the retainer plate is disposed at about a l0 angle with respect tothe horizontal. At the upper or latched position, the retainer plate 57is disposed at about a 20 angle to the horizontal.

in order to urge the top sheet 13 of the paper stack lil against thecylinders 37 and 39 of the feed roller means 12, the biasing means 65are provided. The biasing means include a plate 67 which dependsdownwardly from the retainer plate 57 near the unpivoted end thereof.The plate 67 is provided with a plurality of holes 69 along the oppositevertical edges thereof. A pair of levers 71 are pivotally secured inopenings near the unpivoted end of the retainer plate 57 by pivots 75.

The levers are L-shaped, being pivoted at the juncture of their twogenerally perpendicular sections or portions. The upper portions of thelevers engage the underside of the floor 16 of the tray near their ends.The lower sections of the levers are provided with a plurality of holes77 therein.

In order to urge the upper ends of the levers 71 against the undersideof the floor 16, a pair of coil-type tension springs 79 are provided.Each of the springs extends from one of the holes 77 in the levers 71 toone of the holes 69 at the nearest edge of the plate 67. The size of thesprings is selected to provide the desired biasing force of the topsheet 13 of the paper stack 11 against the cylinders 37 and 39. Thisforce may be adjusted by selecting the proper holes 77 and 69 forsecuring the ends of the springs 79. The force which the springs supplyis selected to exceed the weight of the paper by the required amount.The scale or spring constant of each spring is selected so that, aspaper is consumed and both the weight and the height of the stack isreduced, the springs maintain, at an approximately constant pressure,the top sheet against the cylinders 37 and 39.

Two separator arms 83 and 85 are secured by pivots 87 and 89,respectively, to the sides 19 and 21 of the tray 10. A pair ofsupporting brackets 91 and 93 are mounted to the ends of the arms 83 and85, respectively, and support a pair of pressure members or wedges 14and 15, respectively. The wedges are of triangular cross section and areof a resilient plastic material. The supporting brackets are of aconfiguration such that the wedges are supported inclined at an angle ofabout 30 to the vertical. The upper end of each wedge is above the topsheet 13 of the stack 11 and slightly inside the edge of the top sheet.The lower end of the wedges are below the top sheet of the stack and areoutside of the outer edges of the top sheet. The wedges press on thecorner of the stack in a region near the lower or trailing edge of thesheets, that is, the end of the sheets farthest from the feed rollermeans 12. The arms are of a sufficient weight as to urge the wedgesdownwardly such that they contact the upper corners of the stack ofpaper and cause the upper sheets to buckle slightly. The top sheet willbuckle more than the other sheets because of the slant of the wedges,thereby effecting separation. A pair of legs 99 are provided on the arms83 and-85, respectively to support the arms well above the tray 10 (showin phantom in FIG. 1) and thereby remove the wedges from contact withthe paper when the apparatus is being loaded.

In operation, the clutch (not shown) may be engaged to cause the motor(also not shown) to rotate the axle 41 and the cylinders 37 and 39.Although because of buckling produced by weight on the wedges l4 and 15,the top sheet may be separated somewhat from the sheet immediately belowit due to greater buckling of the top sheet, the separation may beinsufficient to insure reliable operation. In accordance with theinvention, reliability is enhanced by producing forces which causefurther buckling of the top sheet without buckling the sheets below it.Because the cylinders 37 and 39 engage the top sheet further inwardlyfrom its edges than the wedges l4 and 15, lines or vectors of tension inthe top sheet are produced by the cylinders. These vectors extend fromthe point of engagement of each wedge with the top sheet to the point ofengagement of the respective cylinders. As may be seen in FIG. 3, thereis an inwardly directed component to each of the vectors, 95 and 97 sothe trailing corners of the paper are forced slightly toward each otheras seen in FIG. 4. Since the top sheet is buckled more than the sheetsbelow it, the top sheet is cleanly separated from the stack so that onlythe top sheet is fed to the takeup rollers 43 and 45.

The angle at which the tray 10 is supported during operation alsoassists in the separation of sheets, as sheets below the top sheet areurged downward by gravity, and hence toward the back 17 of the tray.

When a new stack of sheets is to be loaded in the apparatus,

the latch pins 63 are moved by squeezing the knobs 64 toward each otherto release the latch pins from the latch plates 59. The retainer plate57 is then lowered until it is supported by the pins 63 on the brackets61 (as shown in phantom in FIG. 1). The tray 10 also moves about itspivots 53 to a smaller angle with respect to the horizontal. Thisenables the tra to clear the cylinders 37 and 39 and the rollers 43 and45. he

assembly is then withdrawn, by sliding the base 47 out of the copyingmachine cabinet on the drawer slide assemblies. A new stack of paper maythen be placed in the tray under the wedges l4 and 15 on arms 83 and 85(as shown in phantom in FIG; ll). The inclined position of the tray 10assists in the proper location of the stack of paper in the tray, as thestack is urged by gravity toward the back 17. When loaded, the apparatusis returned to its original position within the frame or cabinet of thecopy machine. The retainer plate 57 is then raised until the latch pins63 are again supported by the latch plates 59. This causes the tray tobe pushed upwardly by the biasing means 65 so that the top sheet isurged against the cylinders 37 and 39. The apparatus is thereby readyfor operation.

It may therefore be seen that the invention provides improved feedingapparatus which is of simple construction and which is reliable inoperation. The apparatus is capable of operation with a variety of stackheights and with sheets of various thickness and surface quality. Bycausing an initial buckling of the top sheet due to the downward forceof the wedges l4 and 15, and by producing a further operational bucklingof the top sheet due to the position of the cylinders 37 and 39 withrespect to the wedges, the top sheet is cleanly separated from theremainder of the stack for consistently reliable operation.

Various modifications of the invention, in addition to those shown anddescribed herein, will become apparent to those skilled in the art fromthe foregoing description and accompanying drawings. Such modificationsare intended to fall within the scope ofthe appended claims.

What I claim is:

1. Apparatus for individually feeding flexible sheets from a stackthereof, comprising, means for supporting the stack, roller meansdisposed to be in frictional engagement with the top sheet of the stacktoward one edge of the top sheet intermediate the side edges thereof,and a pair of pressure members disposed to be in frictional engagementwith the top sheet of the stack toward the edge of the top sheetopposite said one edge and at the opposite side edges thereof and toproduce forces thereon exerted toward each other, said roller meansengaging the top sheet at a region displaced inwardly of the side edgesof the sheet at a distance sufficient to produce inward displacement ofthe side edges of the sheet in the region of said pressure members whensaid roller means are turned to feed the top sheet, thereby separatingthe top sheet from the sheet below, said supporting means including atray positioned below said roller means for receiving the stack, meansfor resiliently biasing said tray upwardly toward said roller means, aretainer plate disposed below said tray and supporting said biasingmeans, and a slidable base supporting the said retainer plate and saidtray, said retainer plate being pivotally mounted to said base.

2. Apparatus according to claim 1, wherein said biasing means include atleast one pivotal lever having a fulcrum fixed with respect to saidretainer plate and having a first portion displaced from said fulcrumand engaging the underside of said tray, said biasing means furtherincluding a spring secured to a second portion of said lever displacedfrom said fulcrum and said first portion.

1. Apparatus for individually feeding flexible sheets from a stackthereof, comprising, means for supporting the stack, roller meansdisposed to be in frictional engagement with the top sheet of the stacktoward one edge of the top sheet intermedIate the side edges thereof,and a pair of pressure members disposed to be in frictional engagementwith the top sheet of the stack toward the edge of the top sheetopposite said one edge and at the opposite side edges thereof and toproduce forces thereon exerted toward each other, said roller meansengaging the top sheet at a region displaced inwardly of the side edgesof the sheet at a distance sufficient to produce inward displacement ofthe side edges of the sheet in the region of said pressure members whensaid roller means are turned to feed the top sheet, thereby separatingthe top sheet from the sheet below, said supporting means including atray positioned below said roller means for receiving the stack, meansfor resiliently biasing said tray upwardly toward said roller means, aretainer plate disposed below said tray and supporting said biasingmeans, and a slidable base supporting the said retainer plate and saidtray, said retainer plate being pivotally mounted to said base. 2.Apparatus according to claim 1, wherein said biasing means include atleast one pivotal lever having a fulcrum fixed with respect to saidretainer plate and having a first portion displaced from said fulcrumand engaging the underside of said tray, said biasing means furtherincluding a spring secured to a second portion of said lever displacedfrom said fulcrum and said first portion.